I have an Option 61 powered by a MFA150 DC power supply with two MPR25 rectifiers. Normally they share the load. I now have a fan alarm light intermittently on one of the MPR25s. It comes on for a fraction of a second, then goes out. This in turn shuts down the MPR and the remaining unit takes the full 21A load.

It got worse (more frequent) when I tried to blow out dust from the front of the unit. Now it happens every 2 to 15 seconds.

Do I have an imminent fan failure? Can anyone point me towards a source for a replacement fan? Or any other suggestions?

Also, the batteries are probably the original ones - 15? years old. Is there a suggested life span for those? They are labeled Absolyte IIP, type 50A-07.